DGA-grafting pyridine for ultra-selective and prior extraction of 99TcO4− from simulated spent nuclear fuel
Qiang Wu, Wenya Tai, Xiaopei Qi, Huaixin Hao, Weijia Wang, Zhipeng Wang, Fei Wu, Ze‐Yi Yan
Abstract
Selective and prior extraction of 99 TcO 4 − ahead of uranium and plutonium separation is a beneficial strategy for the modern nuclear fuel cycle . Herein, a novel DGA-grafting pyridine ligand BisDODGA-DAPy ( L1 ) was tailored for the efficient separation of TcO 4 − from simulated spent nuclear fuel based on the selectivity of pyridine and synergistic effect of diglycolamide (DGA) group. Compared to the ligands BisDOSCA-DAPy ( L2 ) and BisDODGA-MPDA ( L3 ) with similar structure, BisDODGA-DAPy ( L1 ) demonstrated the better separation performance including good extraction efficiency, reusability, and high loading capacity for TcO 4 − under high acidic medium. The interactions of the ligands with Tc(VII)/Re(VII) have been investigated in detail using FT-IR, 1 H NMR titration , UV-Vis spectrophotometric titration, ESI-HRMS and DFT simulations. The extraction mechanism affected by the protonation of ligand was elucidated under different acidity. BisDODGA-DAPy ( L1 ) demonstrated the ultra-selective extraction ability for TcO 4 − from simulated spent nuclear fuel. The maximum SF Tc/U and SF Tc/Pu values were up to 1.29 × 10 4 and 5.08 × 10 3 , respectively. In the presence of 9 × 10 4 -fold excess of NO 3 − , the extraction of TcO 4 − was almost unaffected. Moreover, the good radiolytic stability further highlights the promising potential of this ligand for 99 Tc separation. DFT calculation revealed the dominant role of DAPy and DODGA in TcO 4 − extraction, providing the theoretical evidence for BisDODGA-DAPy ( L1 ) to selectively bind TcO 4 − over NO 3 − .